The number of channels for transmitting information has been significantly increased since the rapid development of local area network (LAN) and the Internet in the recent years. As a result, the speed and quality of information transmission are also improved. Further, the cost of information transmission is lowered as the price of high performance computer is lowered. This also greatly increases the convenience and generality of information transmission. Now it is common to transmit information through network within an organization or between two organizations. Conventionally, for the purpose of increasing the transmission rate of network, a network manufacturer may aggregate a plurality of low transmission speed signal lines in the network to form a trunk through a network switch system. This trunk may further form a line having wider bandwidth. As a result, the transmission rate and efficiency of a conventional network system is increased through the network switch system. The technique of aggregating a plurality of low speed signal lines is called link aggregation.
A typical network switch system aimed at fulfilling above need is illustrated in FIG. 1. As shown, network switch system 10 comprises ten 10 Megabit network lines (i.e., a trunk) 20, a first network switch 11, and a second network switch 12. In operation, a data stream containing packages is sent from terminal 4 in one computer to first network switch 11. At first network switch 11, a numbering of data stream is performed prior to sending to one of a variety of channels formed by the trunk 20. The packages are further sent to second network switch 12 at a rate of about 100 Megabit per second. At second network switch 12, a decoding is performed on the package for obtaining an original data stream. Finally, a data stream containing the original packages is sent to terminal 3 in another computer. This completes the transmission of data package. Theoretically, above technique may increase the transmission rate and efficiency of a conventional network system. In fact, however, as specified by IEEE 802.3ad it is not allowed to fragment a data package in a trunk into a plurality of sub packages in the network switch system during transmitting. This regulation may force a network designer to sacrifice the increase of transmission rate for maintaining the integrity of data package during transmitting in designing such network switch system.
Referring to FIG. 2, in the FIG. 1 network switch system, first network switch 11 may number each of 12 packages in data stream A to be transmitted. Thereafter, the packages are sent to 10 channels formed by trunk 20. The packages are further sent to second network switch 12 at a rate of about 100 Megabit per second. As shown, number 1 package is the longest. As such, the time occupied by the number 1 package at channel is the longest. Likewise, number 7 package is the shortest. As such, the time occupied by the number 7 package at channel is the shortest. As such, when number 7 package arrives at second network switch 12, the number 1 package still occupies the channel for waiting to transmit. As such, second network switch 12 must wait a predetermined period of time until all data packages in the same trunk are received. Then, a decoding may be performed on the packages. For the integrity of data during transmitting, the longest package of a previous trunk is taken as a base for processing a trunk next to receive. Further, first network switch 11 sends packages at the same timing clock. This may create a time delay Td between two adjacent packages in each channel. As a result, a desired transmission rate is not achievable by such network system.
Referring to FIG. 3, this diagram shows packages of each trunk sent at different timing clocks in the network switch system. The first network switch 11 sets the head of each package of a data stream as a base. Further, a time gap Ts is inserted in the end of each package of a trunk. The second network switch 12 may identify each package of various trunks in the same channel based on the time gap Ts. However, the previous design suffered from a disadvantage. For example, first and second network switches 11 and 12 are interconnected by a signal line (e.g., twisted pair line) for configuring the network switch system. Thus, it tends to create different propagation delays in each formed channel 20 due to the length difference between signal lines. As such, second network switch 12 may not be able to correctly identify the time gap Ts. And in turn, the network system may not correctly number the packages. As a result, a uniform receiving of packages is not achievable. At this condition, a software tool at upper layer having the sorting capability is required to perform the unfinished task. Otherwise, the ordering of packages in trunk may not be maintained. As a result, it tends to cause error in identifying and transmitting data packages.